Naturally-occurring compounds that have been shown to improve insulin sensitivity include Cr and polyphenols found in cinnamon (Cinnamomon cassia). These compounds also have similar effects on insulin signalling and glucose control. The signs of Cr deficiency are similar to those for the metabolic syndrome and supplemental Cr has been shown to improve all these signs in human subjects. In a double-blind placebo-controlled study it has been demonstrated that glucose, insulin, cholesterol and HbA1c are all improved in patients with type 2 diabetes following Cr supplementation. It has also been shown that cinnamon polyphenols improve insulin sensitivity in in vitro, animal and human studies. Cinnamon reduces mean fasting serum glucose (18–29%), TAG (23–30%), total cholesterol (12–26%) and LDL-cholesterol (7–27%) in subjects with type 2 diabetes after 40 d of daily consumption of 1–6 g cinnamon. Subjects with the metabolic syndrome who consume an aqueous extract of cinnamon have been shown to have improved fasting blood glucose, systolic blood pressure, percentage body fat and increased lean body mass compared with the placebo group. Studies utilizing an aqueous extract of cinnamon, high in type A polyphenols, have also demonstrated improvements in fasting glucose, glucose tolerance and insulin sensitivity in women with insulin resistance associated with the polycystic ovary syndrome. For both supplemental Cr and cinnamon not all studies have reported beneficial effects and the responses are related to the duration of the study, form of Cr or cinnamon used and the extent of obesity and glucose intolerance of the subjects.
Cinnamon, the dry bark and twig of Cinnamomum spp., is a rich botanical source of polyphenolics that has been used for centuries in Chinese medicine and has been shown to affect blood glucose and insulin signaling. Cinnamon’s effects on blood glucose have been the subject of many clinical and animal studies; however, the issue of cinnamon intake’s effect on fasting blood glucose (FBG) in people with type 2 diabetes and/or prediabetes still remains unclear. A meta-analysis of clinical studies of the effect of cinnamon intake on people with type 2 diabetes and/or prediabetes that included three new clinical trials along with five trials used in previous meta-analyses was done to assess cinnamon’s effectiveness in lowering FBG. The eight clinical studies were identified using a literature search (Pub Med and Biosis through May 2010) of randomized, placebo-controlled trials reporting data on cinnamon and/or cinnamon extract and FBG. Comprehensive Meta-Analysis (Biostat Inc., Englewood, NJ, USA) was performed on the identified data for both cinnamon and cinnamon extract intake using a random-effects model that determined the standardized mean difference ([i.e., Change 1(control) – Change 2(cinnamon)] divided by the pooled SD of the post scores). Cinnamon intake, either as whole cinnamon or as cinnamon extract, results in a statistically significant lowering in FBG (-0.49±0.2 mmol/L; n=8, P=.025) and intake of cinnamon extract only also lowered FBG (-0.48 mmol/L±0.17; n=5, P=.008). Thus cinnamon extract and/or cinnamon improves FBG in people with type 2 diabetes or prediabetes.
Background: According to previous studies, cinnamon may have a positive effect on the glycaemic control and the lipid profile in patients with diabetes mellitus type 2. The aim of this trial was to determine whether an aqueous cinnamon purified extract improves glycated haemoglobin A1c (HbA1c), fasting plasma glucose, total cholesterol, low-density lipoprotein (LDL), high-density lipoprotein (HDL) and triacylglycerol concentrations in patients with type 2 diabetes.
Methods: A total of 79 patients with diagnosed diabetes mellitus type 2 not on insulin therapy but treated with oral antidiabetics or diet were randomly assigned to take either a cinnamon extract or a placebo capsule three times a day for 4 months in a double-blind study. The amount of aqueous cinnamon extract corresponded to 3 g of cinnamon powder per day.
Results: The mean absolute and percentage differences between the pre- and postintervention fasting plasma glucose level of the cinnamon and placebo groups were significantly different. There was a significantly higher reduction in the cinnamon group (10·3%) than in the placebo group (3·4%). No significant intragroup or intergroup differences were observed regarding HbA1c, lipid profiles or differences between the pre- and postintervention levels of these variables. The decrease in plasma glucose correlated significantly with the baseline concentrations, indicating that subjects with a higher initial plasma glucose level may benefit more from cinnamon intake. No adverse effects were observed.
Conclusions: The cinnamon extract seems to have a moderate effect in reducing fasting plasma glucose concentrations in diabetic patients with poor glycaemic control.
To determine the effects of a dried aqueous extract of cinnamon on antioxidant status of people with impaired fasting glucose that are overweight or obese.
Twenty-two subjects, with impaired fasting blood glucose with BMI ranging from 25 to 45, were enrolled in a double-blind placebo-controlled trial. Subjects were given capsules containing either a placebo or 250 mg of an aqueous extract of cinnamon (Cinnulin PF) two times per day for 12 weeks. Plasma malondialdehyde (MDA) concentrations were assessed using high performance liquid chromatography and plasma antioxidant status was evaluated using ferric reducing antioxidant power (FRAP) assay. Erythrocyte Cu-Zn superoxide (Cu-Zn SOD) activity was measured after hemoglobin precipitation by monitoring the auto-oxidation of pyrogallol and erythrocyte glutathione peroxidase (GPx) activity by established methods.
FRAP and plasma thiol (SH) groups increased, while plasma MDA levels decreased in subjects receiving the cinnamon extract. Effects were larger after 12 than 6 weeks. There was also a positive correlation (r = 0.74; p = 0.014) between MDA and plasma glucose.
This study supports the hypothesis that the inclusion of water soluble cinnamon compounds in the diet could reduce risk factors associated with diabetes and cardiovascular disease.
Based on insulin potentiating activity of cinnamon, effects of a water extract of cinnamon were tested in a 2-mo double-blind placebo trial with 137 participants in China. Mean±SEM age was 61.3 ± 0.8 years, BMI was 25.3 ± 0.3 and M/F ratio was 65/72. A placebo capsule or a 250 mg dried water-extract cinnamon (CinSulin) capsule was given twice per day. At baseline, homeostasis model assessment-estimated insulin resistance (HOMA-IR) was significantly correlated with diastolic blood pressure (r=0.23) postprandial glucose (r=0.45) and insulin (r=0.42), triglycerides (r=0.29), fructosamine (0.23), BMI (r=0.29) and negatively correlated with HDLC (r=0.37). After 2 mo, fasting glucose decreased (p<0.001) in the aqua-cinnamon-supplemented group (8.85 ± 0.36 to 8.19 ± 0.29 mmol/L) compared with 8.57 ± 0.32 to 8.44 ± 0.34 mmol/L in the placebo group (p=0.45). Glucose 2 h after a 75 g carbohydrate load also decreased (p<0.0001) with CinSulin (15.09 ± 0.57 to 13.30 ± 0.55 mmol/L) compared to 14.18 ± 0.60 to 13.74 ± 0.58 mmol/L with placebo. Insulin concentrations and HOMA-IR tended to be improved by aqua-cinnamon supplements but differences were not significant. In summary, supplementation of a water extract of cinnamon had beneficial effects in subjects with hyperglycemia. (Supported by USDA-ARS, Tang-An Medical & Oklahoma State Univ).
Cinnamon extract has been shown to reduce insulin resistance in in vitro and in vivo studies by increasing phosphatidylinositol 3-kinase activity in the insulin signaling pathway and thus potentiating insulin action. Fifteen women with polycystic ovary syndrome (PCOS) were randomized to daily oral cinnamon and placebo for 8 weeks. Comparisons of post-treatment to baseline insulin sensitivity indices using fasting and 2-hour oral glucose tolerance tests showed significant reductions in insulin resistance in the cinnamon group but not in the placebo group. A larger trial is needed to confirm the findings of this pilot study and to evaluate the effect of cinnamon extract on menstrual cyclicity. (Fertil Steril 2007;xx:xxx. ©2007 by American Society for Reproductive Medicine.)
The purpose of this study was to determine the effects of supplementation with a water-soluble cinnamon extract (Cinnulin PF®) on body composition and features of the metabolic syndrome.
Twenty-two subjects with prediabetes and the metabolic syndrome (mean ± SD: age, BMI, systolic blood pressure [SBP], fasting blood glucose [FBG]: 46.0 ± 9.7 y; 33.2 ± 9.3 kg/m2; 133 ± 17 mm Hg; 114.3 ± 11.6 mg/dL) were randomly assigned to supplement their diet with either Cinnulin PF® (500 mg/d) or a placebo for 12-weeks. Main outcome measures were changes in FBG, SBP, and body composition measured after 12-weeks of supplementation. The primary statistical analyses consisted of two factor (group × time), repeated-measures ANOVA for between group differences over time. In all analyses, an intent-to-treat approach was used and significance was accepted at P < 0.05.
Subjects in the Cinnulin PF® group had significant decreases in FBG (-8.4%: 116.3 ± 12.8 mg/dL [pre] to 106.5 ± 20.1 mg/dL [post], p < 0.01), SBP (-3.8%: 133 ± 14 mm Hg [pre] to 128 ± 18 mm Hg [post], p < 0.001), and increases in lean mass (+1.1%: 53.7 ± 11.8 kg [pre] to 54.3 ± 11.8 kg [post], p < 0.002) compared with the placebo group. Additionally, within-group analyses uncovered small, but statistically significant decreases in body fat (-0.7%: 37.9 ± 9.2% [pre] to 37.2 ± 8.9% [post], p < 0.02) in the Cinnulin PF® group. No significant changes in clinical blood chemistries were observed between groups over time.
These data support the efficacy of Cinnulin PF® supplementation on reducing FBG and SBP, and improving body composition in men and women with the metabolic syndrome and suggest that this naturally-occurring spice can reduce risk factors associated with diabetes and cardiovascular diseases.
To investigate the association between vitamin D status, assessed by plasma 25-hydroxyvitamin D, and risk of incident diabetes.
Prospective observational study with a mean follow-up of 2.7 years in the Diabetes Prevention Program (DPP), a multicenter trial comparing different strategies for prevention of diabetes in patients with prediabetes. We assessed the association between plasma 25-hydroxyvitamin D, measured repeatedly during follow-up, and incident diabetes in the combined placebo (n = 1,022) and intensive lifestyle (n = 1,017) randomized arms of the DPP. Variables measured at multiple study time points (25-hydroxyvitamin D, BMI, and physical activity) entered the analyses as time-varying “lagged” covariates, as the mean of the previous and current visits at which diabetes status was assessed.
After multivariate adjustment, including for the DPP intervention, participants in the highest tertile of 25-hydroxyvitamin D (median concentration, 30.1 ng/mL) had a hazard ratio of 0.72 (95% CI 0.56–0.90) for developing diabetes compared with participants in the lowest tertile (median concentration, 12.8 ng/mL). The association was in the same direction in placebo (0.70; 0.52–0.94) versus lifestyle arm (0.80; 0.54–1.17).
Higher plasma 25-hydroxyvitamin D, assessed repeatedly, was associated with lower risk of incident diabetes in high-risk patients, after adjusting for lifestyle interventions (dietary changes, increased physical activity, and weight loss) known to decrease diabetes risk. Because of the observational nature of the study, the potential association between vitamin D and diabetes needs to be confirmed in intervention studies.